“When I say to the righteous that he will surely live, if he trusts to his righteousness and commits iniquity, none of his righteous deeds will be remembered. But in his iniquity which he has committed, in that will he surely die.”
The warning here is against one who has lived rightly and therefore is confident that he deserves the goodwill of God. So he feels that God now owes him something and that he can turn to sin without losing God's goodwill. That is the belief that a man's destiny depends on the quantity of his good works. But that is denied here. It is here clearly stated that God's judgment on a man is not determined by the quantity of his righteousness but by his revealed attitude of heart.
In ancient days many believed that the sins of men were put in the balances on one side and the good on the other, and a man would receive according to which weighed the heaviest. Their view was that if a man had lived a righteous life he could get away with a bit of sinfulness. But Ezekiel gives a firm and emphatic denial of such an idea. It mattered not what the weight of a man's sins was, nor what the weight of his righteous deeds. What mattered was whether his heart was set rightly towards God. And only a man whose heart was rightly set towards God could be sure that he would live and not die. Only he could look forward with confidence to the favour of God.